Fat Free Mass Index Calculator (FFMI)

Whether you’re a fitness enthusiast, a bodybuilder or you’re simply interested in learning your stats, you can use this Fat Free Mass Index Calculator (FFMI Calculator). With it, you can acquire a lot of information about yourself without having to check an FFMI chart or an FFMI scale. Read on to learn more about using this calculator and how to compute the values manually using the different formulas.

Loading Calculator…

How to use the fat free mass index calculator?

 If you’re interested in finding out your fat free mass index or FFMI, this calculator will make the task easier. Just follow these simple steps:

  • Before you can use the fat free mass index calculator, you need to know your height and weight.
  • Choose the unit of measurement for your height from the drop-down menu, either centimeters or feet, then enter the value.
  • Choose the unit of measurement for your weight from the drop-down menu, either kilograms or pounds, then enter the value.
  • Then enter the percentage value of your body fat.
  • After entering all these values, the calculator will automatically generate your Fat-Free Mass, Body Fat, Fat-Free Mass Index (FFMI), and Adjusted (Normalized) FFMI.


How do I calculate my fat free weight? 

If you don’t want to manually compute your fat free weight and compare it with the fat free index, then you can use this online FFMI calculator. This is a health tool you can use to evaluate your body mass while also checking your fat and muscle mass.

To get all the values you need, you must first know your height, weight, and the percentage of your body fat. This is a flexible online calculator since you can use metric or English measurements and get different calculations.

But you may also calculate your fat-free weight on your own using this formula:

fat free weight (FFMI) = (Lean / 2.2) / ((Height in ft x 12.0 + in) x 0.0254)2 x 2.20462

You can also manually calculate your lean weight and adjusted fat free weight with these formulas:

lean weight = Weight in kg x (1.0 – (Body fat %/ 100.0))

adjusted fat free weight (FFMI) = FFMI + (6.1 x (1.8 – ((Height in ft x 12.0 + in) x 0.0254)))


What percent of body fat is obese? 

If you want to determine whether someone is obese or not, there are some factors to consider including gender, body type, age, activity, and heredity. For example, the healthy body fat percentage range in men is usually lower than that of women because women require more fat in their bodies.

What percent of body fat is obese

We all need a specific amount of fat to maintain our bodily functions. This fat helps regulate the temperature of the body, cushions the tissues and organs, and it’s also the primary form of the energy storage of the body. Although the body needs fat, you should only have the appropriate amounts to stay healthy. If you have a high percentage of fat in your body, this will qualify you as obese. For reference, here are the percentage values of obesity:


  • 20-40 years old: more than 39%
  • 41-60 years old: more than 40%
  • 61-79 years old: more than 42%


  • 20-40 years old: more than 25%
  • 41-60 years old: more than 27%
  • 61-79 years old: more than 30%

What is a good body fat percentage?

 According to a study done in 1991, you can accurately estimate the body percentage of adults via the measurements of their skin-folds. You can also use bioelectrical tests which follow specific gender-based formulas in combination with the BMI. However, this calculation isn’t very accurate for people who are very overweight as the value is slightly overestimated. You can also calculate your body fat percentage using the following formulas:

For women: (1.20 x BMI) + (0.23 x Age) – 5.4 = Body Fat Percentage

For men: (1.20 x BMI) + (0.23 x Age) – 16.2 = Body Fat Percentage

For both men and women, there are healthy body fat percentage values which we should all strive to have. These are:


  • 20-40 years old: 21-33%
  • 41-60 years old: 23-35%
  • 61-79 years old: 24-36%


  • 20-40 years old: 8-19%
  • 41-60 years old: 11-22%
  • 61-79 years old: 13-25%


What is my lean body mass?

The lean body mass refers to how much weight you carry which isn’t fat. Fitness enthusiasts and bodybuilders aim to reduce their weight while maintaining the same lean body mass. In other words, they strive to reduce the fat in their body but keep their lean muscles. If you want to find out about your lean body mass, you should first find out your body’s fat percentage.

Your lean body mass doesn’t essentially specify your fat free mass. This is because lean body mass still contains around 3% of fat that’s found in your internal organs, the marrow of your bones, and in your central nervous system. You measure the lean body mass in terms of density.


How do you calculate muscle index? 

The lean body mass is also called the muscle index or the muscle mass percentage. This refers to the bone and muscle tissue in the body along with the water in the body and in the organs.

Muscle index is basically everything except for the fat found underneath the skin’s surface. Calculating the muscle index will allow you to determine how much of your body’s total weight is lean mass and how much is body fat. Follow these steps to calculate your muscle index:

  • Take your weight using a body fat scale. This type of scale will calculate your body fat percentage automatically.
  • Subtract the value you get from 100 to acquire the percentage of your lean mass.
  • Divide the percentage of your lean mass by 100 to get a decimal value which pertains to the percentage of your lean mass.
  • Finally, multiply this lean mass decimal value by the total weight of your body. The value you get is your muscle index or lean mass weight.